v1.19.0

@esri/arcgis-rest-*

• New Features
  • tree: better support for tree shaking in webpack 7fe91548 #424

@esri/arcgis-rest-groups

• New Features
  • join: new joinGroup and leaveGroup methods fa604dec
• Bug Fixes
  • lock: make passing authentication mandatory when updating groups 14bdf888

@esri/arcgis-rest-items

• Bug Fixes
  • null: dont stringify values in item calls c0f48fc0

@esri/arcgis-rest-webpack-demo

• Documentation
  • tree: add tree shaking demo 7fe91548 #424